The Sonderaktion 1005 (English: Special Action 1005), also called Aktion 1005, or Enterdungsaktion (English: Exhumation Action) began in May 1942 during World War II to hide any evidence that people had been murdered by Nazi Germany in Aktion Reinhard in occupied Poland. The operation, which was conducted in strict secrecy from 1942–1944, used prisoners to exhume mass graves and burn the bodies. These work groups were officially called Leichenkommandos ("corpse units") and were all part of Sonderkommando 1005; inmates were often put in chains in order to prevent escape.